1. We have previously shown that 2-deoxyglucose transport was lower than that of 3-0-methylglucose transport and that a 10 mM glucose preincubation can accelerate the 2-deoxyglucose transport rate up to the 3-0-methylglucose transport rate. We now know that this acceleration can be maintained in the absence of glucose for at least 30 minutes after the removal of the glucose. We had previously shown that a 15-30 min incubation resulted in a maximum acceleration. We are now investigating the amount of time that glucose actually has to be present during this 30 min preincubation in order to obtain the 2-deoxyglucose acceleration. If this period is short (less than 5 min) we will investigate whether this effect is dependent upon protein synthesis. 2. Many investigators have proposed that glucose transport is only rate limiting step in glucose uptake into muscle under both physiological or patho-physiological conditions. This is based on the lack of any measureable intracellation glucose concentrations. However, we have previously shown that there can be "local" accumulation of glucose near the glucose transporter in adipocytes, and that the glucose clearance is decreased at the glucose concentrations where this accumulation occurs. In order to investigate the possibility that glucose uptake into muscle is also not rate limited glucose transport, under all physiological or patho-physiological conditions, we are setting up the rat hind limb perfussion technique and will measure glucose uptake into muscle over a range of glucose and insulin concentrations. We eventually will look at which metabolic steps beyond transport (i.e. oxidation, lactate production or glycogen synthesis), are rate limiting if we find glucose/insulin concentrations where transport is not rate limiting.